A new federal law, the Energy Independence and Security Act of 2007 (EISA), creates new energy efficiency standards for light bulbs sold in California. According to a press release from the California Energy Commission:

While the country will adopt this standard on January 1, 2012, California was given authority to implement the national standards one year earlier to avoid the sale of 10.5 million inefficient 100-watt bulbs in 2011 which would cost consumers $35.6 million in higher electricity bills…

The standard in California states that a 100-watt bulb manufactured on or after January 1, 2011 must use 28 percent less energy (i.e. a 100-watt bulb may not use more than 72 watts). The new 72-watt replacement bulb will provide the same amount of light (i.e. lumens), use less power, and cost less to operate.